考虑竖向荷载作用时液化土中群桩基础水平动力响应

Horizontal Dynamic Response of Pile Group Foundation in Liquefied Soil Under Vertical Load

基于Biot饱和多孔介质理论,考虑液化土的流动特性,建立考虑竖向荷载作用的部分埋入群桩水平振动模型,通过分离变量法、算子分解法,引入桩土耦合及位移连续条件,得到复杂条件下液化土中高桩桩间相互作用因子解和群桩水平动阻抗解.通过参数分析,表明液化土特性和竖向荷载对桩间水平相互作用因子、群桩动阻抗有显著影响,指出同一频率下,群桩水平动刚度随着表层液化土厚度的增加而下降,当液化厚度较大时,动刚度随频率上升显著下降,并出现负刚度;桩顶竖向荷载会降低液化土中的群桩动刚度,液化土厚度越大,削弱效果越明显.

The horizontal vibration model of partially buried pile group under vertical load is established based on Biot saturated porous media theory,considering the flow characteristics of liquefied soil.Considering the pile-soil coupling and continuous displacement conditions,the pile interaction factor solutions and the horizontal dynamic pile impedance solutions in liquefied soil under complex conditions are obtained using the variable separation method and the operator decomposition method.Parameter studies are conducted on liquefied soil characteristics and vertical loadings.The results show that at the same vibration frequency,the horizontal dynamic stiffness of pile group decreases with the increase of surface liquefied soil thickness.When the liquefaction thickness is large,the dynamic stiffness decreases significantly with the increase of frequency,and a negative stiffness appears.Vertical pile top loading can reduce the dynamic stiffness of pile group in liquefaction soils.The weakening effect becomes more obvious with the increase in the thickness of liquefied soil.